Hi I'm Ashik Ajith

ashikajith@gmail.com

 github.com/ashikajith

Purpose 

• Getting Started with Ruby
   
• Having Fun with Ruby (Hope so...)
   
• Not a Tutorial  :-(

History of Ruby (walk through)

• Yukihiro Matsumoto (Ruby Matz)

History of Ruby (walk through)

• Aim to create a OO Scripting Language
   
• A language that is more powerful than Perl, and more object-oriented than Python
   
• Code-named after a gemstone's name (àla Perl)
   
• Released in 1995(v 0.95) - 
   
• Current Version - Ruby (v2.2.3) 

 

"Programming languages must feel natural to programmers."

- Matz, creator of Ruby

Ruby With Numbers

#irb console

2 + 2        #=> 4

2 + 7.14     #=> 9.14   

2 - 5.12      #=> -3.12
        
2 ** 100     #=> 1267650600228229401496703205376

2 / 5        #=>

2 / 5.0        #=> 

Ruby With Objects

#irb console

x = 4

x.class  #=> Fixnum

x = 3.142857 

x.class #=> Float   

x = (2 ** 100) 

x.class  #=> Bignum

puts "I can inject variables here #{x} "  #=> Use double quotes

Ruby With Arrays

#irb console

list = ['a','b','c','d']

list << 'e' 

list.pop          #=> "e"

list              #=> ["a", "b", "c", "d"]

list.push 4       #=> ["a", "b", "c", "d", "4"]

# sort

# insert(pos, ary_elemnt)           

# delete_at(index)

Ruby With Ranges

#irb console

# Exclusive Range

numbers = (1...6)

alphabets = ('a' ... 'j')

range_set = ('abc' ... 'abz') #=> ?

# Inclusive Range

numbers = (1 .. 6)

alphabets = ('a' .. 'j')

Ruby With Hashes

Hash = {key => value}

hash = {1=> 'one', 2=> 'two', 3=>'three'}

hash[1] #=> 'One'

hash[2] #=> 'Two'

another_hash = { 'a' => 1, 'b' => 2, 'c' => 3 }

another_hash.keys    #=> ["a", "b", "c"] 

another_hash.values  #=> [1, 2, 3]

    A Hash is a collection of unique keys and values, Similar to arrays but can use any object type

Ruby With Hashes (Contd..)

#Can Have the values as hash instead of String

vehicles = { 'bikes' => {
                          'honda' => ['CB Uniconorn', 'Dream Yuga', 'Activa'],
                          'royal_enfield' => ['Bullet Classic', 'Deset Storm', 
                                                'Thunder bird']
                         },
             'cars' => {
                          'Ford' => ['Ford Figo', 'Ford Classic']
                        }
            }

vehicles['bikes']['royal_enfield'] #=> ['Bullet Classic', 'Deset Storm',
                                        'Thunder bird']

Ruby With Conditions

if condition
 
    #do something
elsif

    #do something else
end
                                    
do_something if condition


unless condition
  #do something
else
  #do something else  
end
  
#do somthing unless condition

Ruby With Conditions

Switch Statement

age =  5
case age
when 0 .. 2
    puts "between 0 & 2"
when 3 .. 6
    puts "between 3 & 6"
when 7 .. 12
    puts "between 7 & 12"
when 13 .. 18
    puts "between 13 & 18"
else
    puts "No Idea"
end

Ruby With Conditions

While

i = 0
num = 5

while i < num  do
   puts("Inside the loop i = #i" )
   i +=1
end

For

for i in 0..5
   puts "Value of local variable is #{i}"
end

Ruby With Conditions

array_or_range.each do |value|
    puts value
end


3.times do 
    print 'ha'
end


array_or_range.map{|e| e }

array_or_range.map{|e| e*2 }

map with select odd or even

Ruby With Classes and Objects

class Dog
  def greet
    'Woof!'
  end
end

dog = Dog.new
dog.greet       #=> 'Woof!'

Ruby With Constructors and Variables

class Robot
  def initialize(name)
    @name = name 
  end

  def say_hello
    "Hi, I'm #{@name}"
  end
end

robo = Robot.new 'Eva'
robo.say_hello                #=> 'Hi, I'm Eva.'

class Cat
  @@sound = 'Meow' #Class variable 

  def greet
    @@sound
  end
end

garfield = Cat.new
garfield.greet       #=> 'Meow!'

Lets Check what we got !!!

# Creating a plus method 

2.plus 2 #=> 4

3.plus 5 #=> 8

# Override a reverse method

'Transform'.reverse #> 'Transform' or #some_other_msg


# What about Infinity

 1/0   #=> Error or Infinity ? 

#Initialize a hash with a list

Hash['key1', 'value1', 'key2', 'value2']   #=> {"key1"=>"value1", "key2"=>"value2"} 
Hash[1,2,3,4,5,6]    #=> {1=>2, 3=>4, 5=>6}

Lets Check what we got !!!

# Double pipes instead of if condition 

a = nil
b = 12

a = a || b   #=> ?

# Multiplication with Array 

[1, 2, 3] * 3 #= [1, 2, 3, 1, 2, 3, 1, 2, 3]

# Array Flatten

[1,2,3,4,[6,7,8,9],11,12].flatten

%w(Tom Dick Harry)

%x(execute shell command)

%Q(dispaly string with double quotes)

What we have discussed so far..

• What's Ruby
   
• What is Rails (Web applicationFrame Work built in Ruby)
   
• Use of Ruby and Rails
   
• Familiarizing with String, Operators and other Data types in Ruby
   
• Creating and Overriding the  Methods in Ruby

Available Resources for Ruby 

• Try Ruby! (http://tryruby.org/)
   

• Ruby in Twenty Minutes
  (https://www.ruby-lang.org/en/documentation/quickstart/)
   

• Ruby from Other Languages
   

• Ruby Monk (https://rubymonk.com/)

QUESTIONS ??